The present invention relates to ink jet printing and, more particularly, to ink jet printing systems having replaceable ink containers for supplying ink to a printhead. A typical ink-jet printer has a printhead mounted to a carriage that is moved back and forth over print media such as paper. As the printhead passes over appropriate locations on the printing surface, a control system activates the printhead to eject, or jet, ink drops onto the printing surface and form desired images and characters.
To work properly, such printers must have a reliable supply of ink for the printhead. Many ink-jet printers use a disposable print cartridge that can be mounted to the carriage. Such a print cartridge typically includes, in addition to the printhead, a reservoir containing a supply of ink. The print cartridge also typically includes pressure-regulating mechanisms to maintain the ink supply at an appropriate pressure for use by the printhead. When the ink supply is exhausted, the print cartridge is disposed of and a new print cartridge is installed. This system provides an easy, user-friendly way of providing an ink supply for an ink-jet printer.
Other types of ink-jet printers use ink supplies that are separate from the printhead and are not mounted to the carriage. Such ink supplies, because they are stationary within the printer, are not subject to the size limitations of an ink supply that moves with the carriage. Some printers with stationary ink supplies have a refillable ink reservoir built into the printer. Ink is supplied from the reservoir to the printhead through a tube that trails from the printhead. Alternatively, the printhead can include a small ink reservoir that is periodically replenished by moving the printhead to a filling station at the stationary, built-in reservoir. In either alternative, ink may be supplied from the reservoir to the printhead by either a pump within the printer or by gravity flow.